Penicillin derivatives which have acylureido group in .alpha.-position of 6-acylamide side chain are described in Belgium Pat. No. 767,648; German Pat. Nos. 2,025,415 and 2,104,579; Japan Pat. No. 7,107,335; Republic of South Africa Pat. No. 7,103,274; and U.S. Pat. No. 3,933,795.
Conventional processes were usually concerned to methods for preparing acylureido penicillin derivatives in the course which 1-chlorocarbonyl-imidazolidine-2-one as intermediate is synthesized with phosgene gas that have potent toxicity, and then this intermediate has reacted with penicillin derivatives to yield object compounds. U.S. Pat. No. 3,933,795 have reported a process for the preparation of ureidoacetamido-penicillin by the reaction of 6-amino-penicillanic acid and carbonylchloride of the formula: ##STR3## But no process using ethylenediisocyanate as starting material has as yet been reported.